feat: retrocompatibility for commit bd9c541e

Hello, I use isolate in a project, and the way I use it is based on the fact that isolate fails if the sandbox already existed. This operation has changed since this commit: https://github.com/ioi/isolate/commit/bd9c541e279a825ecec6f45622f94b64a2bc1253#diff-2ab74399b765a4b5d6d8b9d094d62c5e61108ba0894c1ee133fa0e275d003b9bL26 So I made this PR to be able to add this option directly to isolate Thank you very much